This study aims to investigate the failure mechanisms of SiCf/SiC composite laminates with reinforced installation holes under out-of-plane tensile loading, with the objective of identifying and validating structural design configurations that improve load-bearing capacity.
A SiCf/SiC composite laminates sub-element with a reinforced installation hole was tested on universal material testing system, and fracture features were examined by scanning electron microscope and optical microscopy. Then, a progressive damage model based on the Hashin failure criterion and progressive damage was built, which demonstrated a high level of consistency with experiment. Furthermore, parametric studies on ply orientation and reinforced configurations were conducted using the finite element model.
Crack initiation occurs in the transition zone and propagates along interlaminar interfaces. Matrix cracking governs the initial damage stage, while SiCf/SiC composite laminates retain partial load-bearing capacity until fiber fracture ensues in the transition zone. The progressive damage model incorporating the Hashin failure criterion and progressive damage accurately predicts damage modes, load-bearing capacity and crack morphology of the sub-elements under out-of-plane loading. The predicted peak load (3478 N) differs by only 10.61% from the experimental peak load (3891 N). Furthermore, increasing 90° plies in the transition zone improves bearing capacity, and reinforced-hole contact geometry significantly affects failure strength.
This work provides an application-oriented failure and optimization framework for SiCf/SiC nozzle regulating plates, integrating out-of-plane tensile experiment on a representative sub-element with a validated progressive damage model.
